1. Field of the Invention
The present invention relates to an optical disc drive apparatus to which a disc recording medium represented by a CD (Compact Disc), a DVD (Digital Versatile Disc), or the like is loaded for reproduction or recording of information.
2. Description of the Background Art
In the optical disc drive apparatus, information is recorded and erased by condensing a light beam emitted from an optical pick-up into a small spot on information recording tracks on a rapidly-rotating disc recording medium (hereinafter, simply referred to as an “optical disc”) and scanning the tracks. When the information recorded on the optical disc is reproduced, the information recording tracks on the rapidly-rotating optical disc are irradiated with a light beam, and the reflected light is received for reading the information.
Generally, the optical disc is loaded to the optical disc drive apparatus of the above-described type by mounting the optical disc on a disc tray drawn out of a cabinet and storing the disc tray in the cabinet by means of a tray moving mechanism. The optical disc loaded in the cabinet is clamped by a turntable and a damper and floats from the disc tray. A high-speed rotation operation of the optical disc is thus enabled.
A variety of types of structures have been invented as the tray moving mechanism described above. For example, Japanese Patent Laying-Open No. 7-57362 and Japanese Utility Model Registration No. 3088851 disclose a general structure of the tray moving mechanism.
FIG. 10 is a schematic top view showing a tray moving mechanism of a conventional optical disc drive apparatus, the disc tray being at a disc-removable position. As shown in FIG. 10, the optical disc drive apparatus includes a cabinet (not shown), a frame 120 arranged in the cabinet, and a disc tray 110 slidably supported by frame 120.
A disc mount portion 112 on which an optical disc is mounted is formed on an upper surface of disc tray 110. An opening 111 is formed in the center of disc tray 110, through which elevation/lowering of the turntable as well as irradiation of the information recording tracks on the optical disc with the light beam emitted from the optical pick-up are allowed. Elevation of the turntable through opening 111 will push up the optical disc mounted on disc mount portion 112 to a chucking position. In addition, irradiation of the information recording tracks on the optical disc with the light beam through opening 111 will enable recording and reproduction of the information.
A supporting portion for supporting disc tray 110 is provided in a sidewall 120a of frame 120. On the other hand, a supported portion supported by the supporting portion of frame 120 is provided at a side edge of disc tray 110. More specifically, the supporting portion of frame 120 includes a guide rib 126, a plurality of guide protrusions 127a, 127b, . . . formed on guide rib 126, and guide tabs 128. Meanwhile, the supported portion of disc tray 110 includes a guide groove 113 provided on a lower surface of disc tray 110. In other words, the plurality of guide protrusions 127a, 127b, . . . provided on frame 120 engage to guide groove 113 provided in disc tray 110, so that disc tray 110 is slidably supported by frame 120. Guide tabs 128 provided in frame 120 serve to prevent disengagement of guide protrusions 127a, 127b, . . . described above from guide groove 113.
A stopper 129 provided in frame 120 abuts on a stopper 115 provided in disc tray 110, so as to prevent failing of disc tray 110.
Power generated by a driving motor 121 is utilized to move disc tray 110. For transmission of the power, components serving as power transmission mechanisms such as a timing belt 122, a gear 123, pinions 124, 125, a rack 132 provided in a slider 130, a protrusion 133 also provided in slider 130, a rack 114 provided in disc tray 110, a guide rail 116 provided on the lower surface of disc tray 110, and the like are used.
FIG. 11 is a partially enlarged view showing a shape of a guide protrusion positioned at the forefront in the optical disc drive apparatus described above, whereas FIG. 12 is a schematic cross-sectional view along the line XII—XII of the optical disc drive apparatus shown in FIG. 11.
As shown in FIGS. 11 and 12, in the conventional optical disc drive apparatus, a guide protrusion 127a positioned at the forefront among guide protrusions 127a, 127b, . . . provided on guide rib 126 is implemented by a boss having a columnar shape and integrally formed with frame 120. Accordingly, guide protrusion 127a positioned at the forefront has been in line contact with a wall surface 113a implementing guide groove 113 provided in disc tray 110.
In the optical disc drive apparatus with the above-described structure, if a force is applied in a direction F in FIG. 10, that is, in a transversal direction with respect to disc tray 110 while disc tray 110 is drawn out and at the disc-removable position, guide protrusion 127a positioned at the forefront is broken. This is because the load is concentrated on guide protrusion 127a positioned at the forefront when disc tray 110 is drawn out and at the disc-removable position. If guide protrusion 127a positioned at the forefront is broken, disc tray 110 may fall at worst, resulting in failure of the optical disc drive apparatus.